As semiconductor technology develops, integrated circuits often contain devices operating at a high voltage level, and other devices operating at a low voltage level. The low voltage devices cannot tolerate a high voltage signal. Device failures happen frequently, when the low voltage devices operate with the high voltage signal. In order to protect the low voltage devices from the high voltage signals, the integrated circuit often includes an input/output (I/O) circuit as an interface between the low voltage devices and the high voltage devices. The I/O circuit allows the low voltage devices to communicate with the high voltage devices, while protecting the low voltage devices from being damaged by the high voltage signals.